Heavy Duty Pavement Design

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Presentation to Prologis Presentation to Prologis China China Heavy Duty Heavy Duty Pavement Design Pavement Design Dr Wei Liu Dr Wei Liu Senior Engineer Senior Engineer Fugro-PMS Ltd, New Fugro-PMS Ltd, New Zealand Zealand

description

Heavy duty pavements are pavements subjected to the extremely heavy wheel loads associated with freight handling vehicles in industrial facilities, such as container terminals and warehouses. Heavy duty pavement need to handle many types of freight handling vehicles, such as forklifts, straddle carriers, gantry cranes and side loaders. The purpose of pavement design is to determine the number, material composition and thickness of different layers within a pavement structure required to accommodate a given loading condition.

Transcript of Heavy Duty Pavement Design

Page 1: Heavy Duty Pavement Design

Presentation to Prologis ChinaPresentation to Prologis China

Heavy Duty Pavement Heavy Duty Pavement DesignDesign

Dr Wei LiuDr Wei Liu

Senior EngineerSenior Engineer

Fugro-PMS Ltd, New ZealandFugro-PMS Ltd, New Zealand

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Presentation OverviewPresentation Overview

IntroductionIntroduction Pavement Design Method for Heavy Pavement Design Method for Heavy

Duty PavementDuty Pavement Case StudyCase Study

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IntroductionIntroduction Pavement is the layered structure on Pavement is the layered structure on

which vehicles will travel. It's purpose is which vehicles will travel. It's purpose is two fold, to provide comfortable and two fold, to provide comfortable and durable surface for the vehicles and to durable surface for the vehicles and to reduce stresses to the underlying soils. reduce stresses to the underlying soils.

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IntroductionIntroduction There are two types of There are two types of

pavement frequently in use pavement frequently in use throughout the world :throughout the world :

• FlexibleFlexible - pavements with - pavements with a bitumen bonded surface.a bitumen bonded surface.

• RigidRigid - Pavements with a - Pavements with a concrete slab surface which concrete slab surface which can be un-reinforced, joint can be un-reinforced, joint reinforced or continuously reinforced or continuously reinforced.reinforced.

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IntroductionIntroduction

What is Heavy Duty Pavements?What is Heavy Duty Pavements?• Pavements subjected to the extremely Pavements subjected to the extremely

heavy wheel loads associated with heavy wheel loads associated with freight handling vehicles in industrial freight handling vehicles in industrial facilities, such as container terminals facilities, such as container terminals and warehouses and warehouses

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IntroductionIntroduction

Common pavement distresses:Common pavement distresses:• Rutting: Rutting: a result of heavy, slow moving traffic.

Common in warm areas. Permanent deformation in the wheel paths .

• Fatigue Cracking: With every passing of a vehicle, pavement layer bends under loading. Over time, layer will crack; propagation of cracks upward eventually reaches the surface. Fatigue cracking occurs as individual cracks interconnect.

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IntrodcutionIntrodcution

What is pavement design?What is pavement design?• The goal of pavement design is to The goal of pavement design is to

determine the number, material determine the number, material composition and thickness of the composition and thickness of the different layers within a pavement different layers within a pavement structure required to accommodate a structure required to accommodate a given loading regime. given loading regime.

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IntroductionIntroduction

Special Issues in heavy duty Special Issues in heavy duty pavement designpavement design• Slow moving or static traffic loadSlow moving or static traffic load• Ultra high load magnitudeUltra high load magnitude• Load WanderingLoad Wandering

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Heavy Duty Pavement Design Heavy Duty Pavement Design MethodMethod

Design PrincipleDesign Principle Empirical Vs Mechanistic Empirical Vs Mechanistic Material CharacterizationMaterial Characterization Load CharacterizationLoad Characterization Pavement Response ModelPavement Response Model Failure ModelsFailure Models

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Heavy Duty Pavement Design Heavy Duty Pavement Design MethodMethod

Design PrincipleDesign Principle• Minimize critical vertical stress in lower Minimize critical vertical stress in lower

layers that result inlayers that result in RuttingRutting

• Minimize critical tensile stresses in Minimize critical tensile stresses in upper layers that result inupper layers that result in

Fatigue crackingFatigue cracking

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Heavy Duty Pavement Design Heavy Duty Pavement Design MethodMethod

Empirical Vs MechanisticEmpirical Vs Mechanistic• Empirical Methods are basedEmpirical Methods are based on the results of on the results of

experiments or experience. experiments or experience. Advantage: Simpler approachAdvantage: Simpler approach Disadvantage: Disadvantage: Cannot cope with novel materials or pavement Cannot cope with novel materials or pavement

structures.structures.

It is “like driving a car by only looking It is “like driving a car by only looking in the rear vision mirror, you could only be sure where in the rear vision mirror, you could only be sure where you had been, but not where you were going” you had been, but not where you were going”

– – Geoff Youdale, Chairman, Austroads Geoff Youdale, Chairman, Austroads

Pavement Research GroupPavement Research Group

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Heavy Duty Pavement Design Heavy Duty Pavement Design MethodMethod

Empirical Vs MechanisticEmpirical Vs Mechanistic• Mechanistic method applies the physics Mechanistic method applies the physics to determine:to determine:

The reaction of structures to loading. The reaction of structures to loading. Distribution of vehicle loads to the underlying soil layers.Distribution of vehicle loads to the underlying soil layers. Need fundamental properties of the materials, pavement Need fundamental properties of the materials, pavement

thicknesses, load characteristics. thicknesses, load characteristics.

Traffic

Climatic data

Design & material property

parameters

Pavement response models ()

Incremental fatigue damage models

Transfer functions

Performance prediction models (rutting, % cracks, etc….)

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Heavy Duty Pavement Design Heavy Duty Pavement Design MethodMethod

Empirical Vs MechanisticEmpirical Vs Mechanistic• Advantages of mechanistic methods:Advantages of mechanistic methods:

Design for new load types (such as super single tires).Design for new load types (such as super single tires). Design with new materials (such as Soilfix stabilized Design with new materials (such as Soilfix stabilized

material).material). Improve reliability of predicting performance.Improve reliability of predicting performance. Using performance related material properties.Using performance related material properties. Use of environmental effects.Use of environmental effects.

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Heavy Duty Pavement Design Heavy Duty Pavement Design MethodMethod

Material CharacterizationMaterial Characterization• SubgradeSubgrade

Characterized by strength and/or stiffness Characterized by strength and/or stiffness • California Bearing Ratio (CBR)California Bearing Ratio (CBR)

Measures shearing resistanceMeasures shearing resistance Units: percentUnits: percent Typical values: 0 to 20Typical values: 0 to 20

• Resilient Modulus (MResilient Modulus (MRR)) Measures stress-strain relationshipMeasures stress-strain relationship Units: MPaUnits: MPa Typical values: 30 to 300 MPaTypical values: 30 to 300 MPa

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Heavy Duty Pavement Design Heavy Duty Pavement Design MethodMethod

Material CharacterizationMaterial Characterization• SubgradeSubgrade

Effect of Moisture ContentEffect of Moisture Content

020406080

100120140160180200

0 5 10 15 20

Moisture Content, %

Mo

du

lus,

MP

a

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Heavy Duty Pavement Design Heavy Duty Pavement Design MethodMethod

Material Material CharacterizationCharacterization• Subbase and Subbase and

RoadbaseRoadbase Elastic Modulus Elastic Modulus E Poisson’s RatioPoisson’s Ratio

Definitions of E and .

D/2

l

l

l = l/l

t = D/D

E =

= l/t

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Heavy Duty Pavement Design Heavy Duty Pavement Design MethodMethod

Material CharacterizationMaterial Characterization• Surface LayerSurface Layer

Asphalt MixAsphalt Mix• Dynamic Modulus E* (Dynamic Modulus E* (Witczak Equation)Witczak Equation)log . . . ( ) . .

.. . . . ( ) .

( . ` . log( ) . log( ))

E V

V

V V e

a

beff

beff af

1249937 0 29232 0 001767 0 002841 0 058097

08022083871977 0 0021 0 003958 0 000017 0 005470

1

200 2002

4

4 38 382

340 6033 3 0 313351 0 393532

• bitumen viscosity

• loading frequency

• air voids

• effective bitumen content

• cum. % retained on 19-mm sieve

• cum. % retained on 9.5-mm sieve

• cum. % retained on 4.76-mm sieve

• % passing the 0.075-mm sieve

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Heavy Duty Pavement Design Heavy Duty Pavement Design MethodMethod

Material CharacterizationMaterial Characterization• Surface LayerSurface Layer

Asphalt MixAsphalt Mix

10

100

1000

10000

-20 -10 0 10 20 30 40 50

Temperature, C

Mo

du

lus,

MP

a

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Heavy Duty Pavement Design Heavy Duty Pavement Design MethodMethod

Material CharacterizationMaterial Characterization• Surface LayerSurface Layer

Porland Cement ConcretePorland Cement Concrete• Elastic ModulusElastic Modulus• Flexural strengthFlexural strength

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Heavy Duty Pavement Design Heavy Duty Pavement Design MethodMethod

Load CharacterizationLoad Characterization• Pavement damagePavement damage

Miner’s lawMiner’s law

• CharacterizationCharacterization SpectrumSpectrum Expressed as a fraction of a standard load Expressed as a fraction of a standard load

• Pavement lifePavement life Expression of how much load repetitions can Expression of how much load repetitions can

be endured before unacceptable be endured before unacceptable serviceabilityserviceability

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Heavy Duty Pavement Design Heavy Duty Pavement Design MethodMethod

Pavement Response ModelPavement Response Model• Layered Elastic AnalysisLayered Elastic Analysis

Each layer is homogenous, isotropic, linearly Each layer is homogenous, isotropic, linearly elastic (E,elastic (E,))

Each layer is weightlessEach layer is weightless Infinite in x, y, finite in z directionInfinite in x, y, finite in z direction Uniform pressure applied over a circular Uniform pressure applied over a circular

areaarea Continuity at layer interfacesContinuity at layer interfaces

• Same: vertical & shear stress Same: vertical & shear stress vertical and radial displacementvertical and radial displacement

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Layer 1HMA

E1

Layer 3Subgrade Soil

E3

h1

h2

No bottom boundary, assume soil goes on infinitely.

Nohorizontalboundary, assumelayersextendinfinitely.

Tire has a total load P, spread over a circulararea with a radius of a, resulting in a contactpressure of p.

PavementReactions

Deflection ()

Tensile Strain (t)

Compressive Strain (Compressive Strain (vv))

Layered Elastic Model Representation of a Pavement

Layer 2Granular

BaseE2

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Heavy Duty Pavement Design Heavy Duty Pavement Design MethodMethod

Pavement Response ModelPavement Response Model• Critical Pavement Responses and LocationsCritical Pavement Responses and Locations

LocationLocation ResponseResponse

Pavement surfacePavement surface Deflection (vertical)Deflection (vertical)

Bottom of HMA layer(s)Bottom of HMA layer(s) Horizontal tensile strainHorizontal tensile strain

Top of intermediate layer Top of intermediate layer (base or subbase)(base or subbase)

Vertical compressive Vertical compressive strainstrain

Top of subgradeTop of subgrade Vertical compressive Vertical compressive strainstrain

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Heavy Duty Pavement Design Heavy Duty Pavement Design MethodMethod

Failure ModelsFailure Models• Fatigue CrackingFatigue Cracking

allowable number of load repetitions related to tensile allowable number of load repetitions related to tensile strain at bottom of asphalt layerstrain at bottom of asphalt layer

AI & Shell design methods -- allowable load repetitions AI & Shell design methods -- allowable load repetitions related to tensile strain and modulusrelated to tensile strain and modulus

NNff = f = f11((tt))-f2-f2(E(E11))-f3-f3

Modulus effect is small (f3 is smaller than f2)Modulus effect is small (f3 is smaller than f2) Several models that include only strain : Several models that include only strain : NNff = f = f11((tt))-f2-f2

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Heavy Duty Pavement Design Heavy Duty Pavement Design MethodMethod

Failure ModelsFailure Models• RuttingRutting

2 procedures to limit rutting2 procedures to limit rutting• limit vertical compressive strain on top of subgradelimit vertical compressive strain on top of subgrade• limit total accumulated permanent deformationlimit total accumulated permanent deformation

AI and Shell design -- allowable number of load AI and Shell design -- allowable number of load repetitions to limit rutting related to vertical repetitions to limit rutting related to vertical compressive strain on top of subgrade compressive strain on top of subgrade

Form (can be used for all materials):Form (can be used for all materials):

pp = a( = a())bb(N)(N)1-m1-m

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Heavy Duty Pavement Design Heavy Duty Pavement Design MethodMethod

Failure ModelsFailure Models• Miner’s HypothesisMiner’s Hypothesis

Provides the ability to sum damage for a Provides the ability to sum damage for a specific distress typespecific distress type

D = D = n nii/N/Ni i 1.0 1.0

where nwhere ni i = actual number of repetitions = actual number of repetitions for load i for load i

NNi i = allowable number of repetitions = allowable number of repetitions for load i for load i

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Case StudyCase Study

Design Conditions:Design Conditions:• A concrete pavement for a heavy duty A concrete pavement for a heavy duty

industrial hardstand with a total industrial hardstand with a total repetition of 182,5000 with a 10 ton axle repetition of 182,5000 with a 10 ton axle load for a period of 5 years. load for a period of 5 years.

• Roadbase is the Soilfix Stabilized Roadbase is the Soilfix Stabilized Aggregate Aggregate

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Case StudyCase Study

Design Inputs:Design Inputs:

LayerLayer MaterialMaterial Thickness Thickness (mm)(mm)

Modulus Modulus (MPa)(MPa)

Poisson’s Poisson’s RatioRatio

11 Porland Cement Porland Cement ConcreteConcrete

200200 30003000 0.150.15

22 Soilfix Stabilized Soilfix Stabilized AggrageAggrage

300300 68906890 0.20.2

33 Compact SoilCompact Soil 0.40.4

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Case StudyCase Study

Pavement Response CalculationsPavement Response Calculations• Critical Stresses in Pavement StructureCritical Stresses in Pavement Structure

Loc# Layer

Coordinates (mm) Normal Stress (kPa) Shear Stress (kPa)

X Y Z X Y Z YZ XZ XY

1 1 0 0 200 -1970.76 -2461.34350.1

9 0 0 0

2 1 171.5 0 200 -2207.53 -2660.59 407 0 0 0

3 3 0 0 500 35.1 35.28 37.04 0 0 0

4 3 171.5 0 500 36.51 36.62 38.49 0 0 0

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Case StudyCase Study

Pavement Response CalculationsPavement Response Calculations• Critical Strains and Displacements in Pavement Critical Strains and Displacements in Pavement

StructureStructure

Loc Layer

Coordinates (mm) Normal MicroStrainDisplacement (micrometer)

X Y Z X Y Z X Y Z

1 1 0 0 200 -82.7 -110.91 50.75 15.3 0 1067.43

2 1 171.5 0 200 -93.47 -119.53 56.86 0 0 1081.58

3 3 0 0 500 42.68 46.84 89.52 -7.59 0 1059.58

4 3 171.5 0 500 45.1 47.91 93.01 0 0 1072.66

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Case StudyCase Study Pavement Life PredictionPavement Life Prediction

• Fatigue Cracking ModelFatigue Cracking Model

• Rutting ModelRutting Model

• Results:Results:

  Fatigue Rutting

Applied Numbers 1825000 1825000

Allowed Numbers 1.54E+07 2.41E+08

Damage Factor 0.12 0.01

MRN f

61.1761.17log

87.3

16 110

vrN

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Thank you!